Pressure sensitive adhesives are useful in making paper labels, vinyl film laminates, decals, and many other related products. The conventional tackified rubber-based paper labels often lose their adhesion properties upon long term exposure to heat or air. The unsaturation of the rubber backbone often requires additional stabilizers such as antioxidants to maintain its pressure sensitive adhesive properties. The high levels of tackifier loading in a rubber-based systems dramatically reduces the cohesive strength of the adhesive. As a result, edge ooze is often observed in large roll label stocks during storage or at converting operations. Tackified acrylic dispersion systems do minimize the oxidative and thermal stability problems of paper labels. However, edge ooze is not completely eliminated due to the impact of the tackifier incorporation. The cohesive strength (shear) value for a pressure sensitive adhesive composition are indicative of its edge oozing tendency.
U.S. Pat. No. 4,322,516 discloses vinyl acetate/ethylene/acrylate copolymers for pressure sensitive adhesives.
U.S. Pat. No. 4,645,711 discloses pressure sensitive adhesives comprising a copolymer of an alkyl acrylate monomer and an emulsifier monomer and also incorporating tackifier resin.
U.S. Pat. No. 4,939,190 discloses an aqueous acrylic emulsion prepared by polymerizing an ethylenically unsaturated monomer composition containing a specific monomer in the presence of a tackifier resin emulsion and then emulsion polymerizing an ethylenically unsaturated monomer composition containing a specific alkyl(meth)acrylate.